It's China's 'Great Wall' for the 21st century. The 3 Gorges Dam spans the legendary Yangtze River for 2.3 km (1.4 miles) and is 185 m (over 600 feet) high. That makes it 5 times bigger than the Hoover Dam. Construction set a world record, using 16 million cubic m (21 million cubic yards) of concrete.

You may know about some of the controversies surrounding the dam. It flooded a 600 km (400 mile) reservoir to 175 feet above sea level. As a result, a million people were displaced, and architectural, cultural, and archeological sites (including 4000 year old cliff side burials of early Ba peoples) as well as farms and forests have disappeared under water. The dam has also had an impact on the river ecology upstream and downstream from the dam. It is blamed for damaging fish populations and the functional extinction of the Chinese river dolphin.

But, like the Hoover Dam in the U.S., Egypt's Aswan Dam, the Panama Canal or other extraordinary feats of human engineering of the planet, the 3 Gorges dam in China's Hubei province is an unforgettable travel experience. Controversies aside, it is awe-inspiring to take in the sheer scale and scope of human endeavor. Yangtze river cruises and most land tours in the region take you to one or more viewing points of the vast dam site.

So here are three things you might not know about this unparalleled structure:

It Protects the Region from Disastrous Flooding

One of the main reasons to build the 3 Gorges dam was to control flooding. The Yangtze river has endured catastrophic flooding events over the centuries. An estimated 300,000 people died in the 20th century alone in floods. Building the dam was designed to control the flow and protect 15 million Chinese and 1.5 million acres of farmland along the Yangtze from deadly river flooding.

It Generates Power

The Three Gorges Dam is the world's largest electric power generating station by installed capacity: 22, 500 MW. More than 2 dozen water-powered turbines produce 20 times the power of the Hoover Dam. Unbelievably, this massive dam produces less than 5% of the total energy needs of this country with 1.4 billion people. (Nearly 5 times the U.S. population and 50 times the population of Canada.)

The electricity produced by the Three Gorges Dam reduces China's use of coal for power generation by an estimated 31 million tonnes each year, preventing 100 million tonnes of greenhouse gas emissions from coal.

It Improves the Environment

The dam's regulation of water levels, and its 'shipping elevator' that increases transit time compared to step locks over river elevations, have facilitated more reliable shipping along the Yangtze. Inland shipping has increased over 5 times since pre-dam days. Barges are replacing trucks, thereby reducing road congestion and carbon dioxide emissions annually by millions of tonnes… directly improving China's (previously famously unimpressive) air quality.

Since the dam opened in 2012, it has blocked more than 10 million tonnes of waste matter including plastic bags, bottles and other garbage that would have otherwise flowed out to sea (but chemical water pollution is unaffected). It even has a garbage-ingesting 'tongue' above the dam, a rolling track on top of a garbage barge that pulls in garbage from the water, preventing it from entering the dam and damaging power generators… as well as flowing downstream to Shanghai and the ocean.

So Should you Travel There?

China's 3 Gorges Dam is a story with many shades of gray. The goals and results of the dam will continue to divide opinion. But it is now an irreversible part of the landscape of China's fabled jade-green Yangtze river, and a destination every visitor to China should see to contemplate the astonishing things humans can achieve… and at what cost.